Drunkenness, in its most common usage, is the state of being intoxicated with alcohol (i.e. ethanol) to a sufficient degree to impair mental and motor functioning. A person who is habitually intoxicated in this manner is labeled an alcoholic, often referred to as a "drunk" (a shortened form of the more traditional term "drunkard") or colloquially as a "lush," "alco" or "jakey".

Drunkenness can also be used to describe the effects of any number of illegal drugs. (More commonly referred to as being "high" or "stoned")